|Carroll, Jeffery - Jeff Carroll|
Submitted to: Livestock Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2012
Publication Date: 1/10/2013
Citation: Falkenberg, S.M., Carroll, J.A., Keisler, D.H., Sartin, J.L., Elsasser, T.H., Buntyn, J.O., Broadway, P.R., Schmidt, T.B. 2013. Evaluation of the endocrine response of cattle during the relocation process. Livestock Science. 151(2-3):203-212. Interpretive Summary: A collaborative study was conducted by scientists from the Livestock Issues Research Unit, Mississippi State University, the USDA-ARS Bovine Functional Genomics Unit, and Auburn University to determine if transportation, in and of itself, is truly a stressful experience for cattle. The study was designed in a manner to mimic the relocation process that cattle experience when being shipping from the farm to a sale barn, held overnight, and then shipped to a second location such as a backgrounding facility or feedlot. To reduce the potential variations within the study that could be caused by animals with differing temperaments, docile Holstein heifers were used for the study. Results from this study support previous research from our laboratory that suggests that the initial handling and exposure to novel environments is more stressful to cattle than the act of being transported. Additionally, the intermittent and relatively mild stress responses observed in this study were not adequate enough to cause changes in hormones that are associated with growth and performance of cattle. Collectively, this data, as well as our previous data, confirm that the lone act of tranportation does not impose a significant stress on cattle. Therefore, future research endeavors should focus on ways to reduce the stress associated with the ovearall relocation process (i.e., handling, processing, loading, transporting, and unloading). Reducing the stress assocaited with the relocation process will undoubtedly improve animal health, performance, and overall well-being. This data will be of interest to scientists in the fields of stress physiology and immunology, beef cattle production, and to cattle producers in general. Ultimately, it is anticipated that this type of data will lead to the development of alternative management practices that will improve the health and performacne of beef cattle.
Technical Abstract: To evaluate the endocrine responses associated with the relocation process, 22 Holstein heifers (326.4±46.8 kg BW) were randomly assigned to control (CON) or relocation (RELOC) treatment groups. On d 0, all heifers were weighed and fitted with indwelling rectal temperature (RT) probes and jugular catheters. On d 1, baseline blood samples were collected for 2 h prior to the transportation event. All heifers were then weighed and CON heifers were returned to tie stalls and RELOC heifers loaded into a modified stock trailer (12 individual stanchions) for a 4 h transportation event. Blood samples were simultaneously obtained from both groups throughout the 4 h transport event (TE-I) at 30-min intervals. After transport, RELOC heifers were unloaded at a location unfamiliar to the heifers, weighed, and placed into tie stalls for a 2 h post-transportation period. Heifers from both treatment groups were then placed into two separate holding paddocks with access to water and hay for 4 h. After 4 h, heifers began hay and water deprivation for a period of 21 h (1500 h on d 1 to 1100 h on d 2). On d 2, the sequence was repeated with RELOC heifers exposed to a second 4 h transport event (TE-II); the timeline and procedures of TE-II identical to that of TE-I. All serum samples were analyzed for concentrations of cortisol, GH, and IGF-I. A 6% reduction in BW for the RELOC heifers as compared to a 2.5% reduction in BW for the CON heifers (P<0.001) was observed during TE-I. Overall BW loss was 2% greater (P>0.02) for RELOC compared to CON heifers. During TE-I, RELOC heifers had greater RT compared to CON heifers. There was a main effect interaction of treatment x time observed for cortisol; RELOC heifers had greater cortisol concentrations at multiple time points throughout TE-I and II. No differences (P>0.05) in area under the curve (AUC) for cortisol were observed during TE-I, but AUC was different for total cortisol during TE-II. Heifers in the RELOC treatment groups had greater cortisol concentrations compared to CON. There were no differences in AUC for GH between the RELOC and CON heifers for TE-I or II, but a transient decline (P<0.05) within each group (RELOC and CON) was observed from d 1 to d 2. Results of this study provide evidence that the relocation process, and more specifically, the actual process of transportation, can elicit a stress response, as indicated by increased serum concentrations of cortisol, increased RT, and increased BW losses.